In modern wind turbines, the pitch angle of the rotor blades can be adjusted to adapt the flow conditions of the rotor blades and the torque produced by the rotor blades to variable operating conditions such as when the unit is turned off, and in particular to adapt to different wind velocities and wind conditions. For this purpose, the rotor blades are usually mounted on the rotor about their longitudinal axis by means of large-diameter roller bearings or plain bearings such that the rotor blades can be rotated about their longitudinal blade axes relative to the rotor hub such that the pitch angle of the rotor blades can be changed. The adjustment unit for adjusting said pitch angle of a rotor blade usually comprises an actuator disposed in the area of the pivot bearing between the rotor hub and the rotor blade and which rotates the two bearing rings of the pivot bearing relative to each other by means of at least one, preferably linearly working adjustment actuator, either by directly engaging in the bearing rings or indirectly in components connected with same such as the rotor hub or the rotor blade itself or with structural parts connected with same such as the reinforcing plates for reinforcing the bearing rings.
WO 2012/069052 A1 describes a wind turbine in which the adjustment unit for adjusting the pitch angle of the rotor blades comprises a pair of hydraulic cylinders for each rotor blade and an associated supply unit with pressure accumulators and control valves mounted on a carrier plate which closes the inner ring of the pivot bearing and is rotationally fixed to the rotary hub. The said supply unit with pressure accumulators and control valves is mounted on the inside, i.e. on the side of the carrier plate facing the rotor hub, while the pair of hydraulic cylinders is mounted on the outside of the carrier plate where it is supported on one side by the carrier plate and on the other side by a structural part connected with the outer ring of the pivot bearing, such that by extending and retracting the hydraulic cylinders the outer ring can be rotated relative to the inner ring and thus the pitch angle of the rotor blade can be adjusted.
Similar pitch adjustment systems for the rotor blades of wind turbines are known from EP 2458209 A2, AU 2009/337882 A1 or WO 2014/009011 A2.
One such adjustment drive is characterized by its compact configuration since an arrangement in the inner space surrounded by the bearing rings can be achieved through the separation of adjustment actuator and supply unit on different sides of the carrier plate. Furthermore, the adjustment drive together with the pivot bearing can be combined in a module that can be pre-assembled.
However, the separation between supply unit and adjustment actuators on opposite sides of the carrier plate leads to the problem that the carrier plate has to comprise relatively large conduit recesses for the supply lines, which reduces the strength of the carrier plate and thus its stiffening effect for the bearing ring. This problem is exacerbated by the fact that the adjustment actuators rotate relative to the carrier plate and thus relative to the adjustment unit when the pitch is adjusted, which means that the conduit openings for the supply lines must be large enough to compensate for the rotational skew. On the other hand, this can lead to a collision problem, especially when—in case of large rotor blades and thus greater forces to be controlled—several adjustment actuators are provided to adjust a rotor blade.
Based on this, it is the object of the present invention to provide an improved wind turbine and an improved adjustment unit for adjusting in particular the pitch angle of a rotor blade, to avoid the disadvantages inherent in the state of the art and to further develop the latter in an advantageous manner. In particular, a small-scale, compact adjustment unit is to be provided which weakens the structure and stiffening of the rotational bearing as little as possible, and which—if possible—circumvents the collision problem when the bearing parts are rotated.
The invention achieves this object by means of a wind turbine with a rotor comprising rotor blades with adjustable pitch angles, and an adjustment unit for adjusting the pitch angle of the rotor blades; wherein the adjustment unit comprises a pivot bearing including at least two coaxial bearing rings that are rotatable against each other, at least one adjustment actuator for rotating the two bearing rings against each other, and a supply unit for supplying the adjustment actuator with energy, wherein the at least one adjustment actuator and the supply unit are disposed on an adjustment drive carrier part which is directly or indirectly rotatably connected with one of the bearing rings and comprises a support bearing for rotatably supporting the adjustment actuator, wherein the adjustment unit is connected with the adjustment actuator by means of at least one pressurized-media channel passing through the support bearing.
It is recommended to integrate the energy supply connection from the supply unit to the at least one adjustment actuator in the rotatable support bearing by which the adjustment actuator is supported on the adjustment drive carrier part and thus on one of the bearing rings. According to the invention, the supply unit is connected with the adjustment actuator by at least one pressure-media channel which passes through the support bearing. Thus, the support bearing has a double function: On the one hand it forms a rotatable linking point for the adjustment actuator, and on the other hand it supplies the energy for the adjustment actuator from the supply unit. That is why no separate cables or tubes are necessary in the carrier part, thus preventing a weakening of the carrier part.
In particular, the rotatable mounting of the supply unit can be combined with the rotatable support or mounting of the at least one adjustment actuator, such that the supply unit and the adjustment actuator can rotate together related to the carrier part, especially such that there is no rotation between the supply unit and the adjustment actuator, but only a joint rotation relative to the carrier part. Due to a joint pivot bearing for the adjustment actuator and the supply unit, a simple configuration with few parts and a space-saving design can be achieved. Furthermore, due to the absence of a rotational skew between the supply unit and the adjustment actuator, the energy supply connection between the supply unit and the adjustment actuator can be of particularly simple configuration.
In an advantageous further development of the invention, the connection between the supply unit and the adjustment actuator can be completely without tubes and cables. The energy supply connection and a control connection that may also be necessary between the supply unit and the adjustment actuator can be integrated into said rotatable support bearing and led only through said support bearing. A part of the bearing structure such as a bearing bolt could comprise at least one energy supply hole for supplying the adjustment actuator with energy. By eliminating separate tube and cable connections, which would have to be conducted through separate duct recesses past the support bearing, not only can a weakening of the carrier part be prevented, but the collision problem mentioned above can be avoided which arises when the bearing rings rotate oppositely and the adjustment actuators begin to swivel, since now, parts of the bearing structure no longer have any bulging cables or tubes. The at least one adjustment actuator may have tubes or lines for pressurized media on its outside or in the form of outside hydraulic pipes, but preferably no tubes or cables are present which would cross the carrier part carrying the adjustment drive.
In another advantageous embodiment of the invention, not only the at least one adjustment actuator, but also the supply unit opposite the carrier part on which the adjustment actuator is supported can be rotatably mounted such that in a pitch position of the rotor blade and thus when the bearing rings are rotating relative to each other, the at least one adjustment actuator as well as its supply unit can rotate or pivot in relation to the adjustment drive carrier part. In this case, the rotatable mounting of the supply unit can be combined especially with the rotatable support or mounting of the at least one adjustment actuator, such that the supply unit and the adjustment actuator can rotate together in relation to the carrier part, especially such that there is no rotation between the supply unit and the adjustment actuator, but only a joint rotation in relation to the carrier part. Due to the absence of rotational skew between the supply unit and the adjustment actuator, the energy supply connection between the supply unit and the adjustment actuator can be of particularly simple configuration.
For example, a bearing journal passing through the carrier part can be provided on which on the one hand the adjustment actuator is supported and on which on the other hand the supply unit is mounted, wherein said bearing journal may comprise at least one pressurized-media channel to connect the supply unit with the adjustment actuator for supplying it with energy. The said bearing journal can be rotatably mounted on the carrier part, for example by means of a suitable roller bearing and/or at least one suitable plain bearing. The components of the supply unit such as the pump, electric motor and pressure accumulator, can be combined in a pre-assembled module that is mounted as a unit on the bearing journal.
One such bearing journal may also be designed as a sleeve or otherwise as a part of the bearing structure on which the adjustment actuator may be supported on one hand and the supply unit on the other hand.
Such a joint rotatability of the adjustment actuator and the supply unit related to the adjustment drive carrier part can be of advantage in particular when only a single adjustment actuator is provided for changing the pitch of the rotor blade or for oppositely rotating the bearing rings, or when separate supply units are provided for changing the pitch of a rotor blade. The latter design can be achieved, for example, when each adjustment actuator is assigned to a supply unit, for example in the form of a pressure accumulator and/or a drivable pump which can be fastened to the bearing journal or a part of the bearing structure as mentioned above, on which the associated adjustment actuator is also supported.
However, in an alternative embodiment of the invention, a joint supply unit for several adjustment actuators can be provided, wherein in this case the supply unit can be non-rotatably mounted on the carrier part. To still accomplish an energy supply through the rotatable support bearings of the adjustment actuator said rotatable support bearings can comprise rotatable ducts for conducting the pressurized media. One such rotatable duct can be integrated in each support bearing, such that a separate rotatable duct is provided for the energy supply of each adjustment actuator. In an alternative embodiment of the invention, only one of the support bearings may be provided with such a rotatable duct, wherein the pressurized means passing through the rotatable duct can be distributed to the various adjustment actuators by a suitable distributor on the actuator side of the carrier part, and wherein the adjustment actuators can be arranged in star-shaped or successively connected form.
The adjustment actuators can be hydraulically connected in parallel or serially supplied by the supply unit in the sense of a master-slave arrangement.
When two adjustment actuators are provided in said manner, these can be arranged to rotate in opposite direction to each other such that to oppositely rotate the two bearing rings, one of the adjustment actuators is extendable and the other is retractable. This prevents the formation of a pendular volume, and the pressure accumulator can be substantially smaller.
However, alternatively or additionally, at least two adjustment actuators can be provided which rotate alike such that to oppositely rotate the two bearing rings, both adjustment actuators are simultaneously extendable and/or retractable.
In another embodiment of the invention, said adjustment drive carrier part which supports the at least one adjustment actuator or the several adjustment actuators, and on which the supply unit is mounted, can be substantially in the form of a plate and/or extend substantially across the rotation axis of the pivot bearing and/or extend over one of the bearing rings in the form of a lid. In particular, said carrier part can extend across the middle of the bearing and/or be connected with several bearing sections, especially also with opposite bearing sections, wherein in case of a plate-like design of the carrier, a revolving or multiple connection with the bearing ring can be provided. The carrier part can have a flat or at least almost continuous plate-like structure and/or it can substantially completely or at least for the most part lock the bearing ring, but it can also be designed in the shape of framework or lattice, or it may only consist of braces. Advantageously, said carrier part forms a stiffening element which stiffens a bearing ring and/or a bearing recess of the rotor hub against twisting, wherein said carrier part can advantageously be rigidly fastened on one of the bearing rings and/or the bearing recess of the rotor hub, for example by means of several threaded bolts.
On the other hand, the at least one adjustment actuator which is supported on said carrier part can be supported directly or indirectly on the other bearing ring that is rotatable relative to the bearing ring that is fastened to said carrier part, such that the two bearing rings can be oppositely rotated through the extension or retraction or through the actuation of the adjustment actuator. Advantageously, the adjustment actuator can be linked to said bearing ring by means of another rotatable support bearing which directly rotatably supports the adjustment actuator on the bearing ring. The said support bearing can be attached directly on the bearing ring or be connected to an intermediate part connected to the bearing ring, for example in the form of a bearing flange or a fastening bracket.
Preferably, the direct or indirect linking of the at least one adjustment actuator to said other bearing ring can be provided by means of a support part which—other than said carrier part on which the other linking point of the adjustment actuator is provided—leaves the middle of the bearing free and is connected with said bearing ring only where the adjustment actuator is linked, i.e. in particular not connected with the opposite or other bearing ring sections. On said one-sided support part which can be designed as a bearing flange or fastening bracket, but also as an integral bearing ring section, a rotatable or articulated support bearing can be provided to support the adjustment actuator. With the one-sided linkage of the adjustment actuator, leaving the middle of the bearing open on said other bearing ring, good access to the at least one adjustment actuator can be achieved on the one hand, and on the other hand, a favourable direct application of force into the bearing ring can be achieved. Furthermore, this creates a maximum length of travel for the adjustment actuator which ensures a wide adjustment range without collision problems.
Another alternative continued development can be that another carrier part, in which said adjustment actuator engages, is rotatably connected with said bearing ring. This additional carrier part can be shaped as a plate as explained above, or it can have another structure and/or form a stiffening part which is connected to said bearing ring in the form of a lid, or it can be fastened to the rotor blade in the section where the bearing recess of the rotor blade is situated.
However, said fastening of the adjustment actuator directly or indirectly on the bearing ring means that the at least one adjustment actuator can be accommodated in a favourable position, providing it with sufficient travel. Also, a direct transmission of force with light-weight construction can be achieved.
In another embodiment of the invention, the outer ring of the pivot bearing can be connected with the rotor hub, and the inner ring with the rotor blade. In principle, an opposite arrangement of the bearing rings would be possible as well. However, a connection of the inner ring with the rotor blade facilitates its attachment to the rotor hub or to the pitch bearing connected to it.
The carrier part to which the at least one adjustment actuator and its supply unit are mounted can advantageously be connected with the outer ring and/or with the rotor hub, in particular in a non-rotatable way, wherein in this case, the second linking point of the at least one adjustment actuator is supported on the inner ring of the pivot bearing. However, in an alternative embodiment of the invention, said carrier part can also be non-rotatably connected with the inner ring, wherein in this case, the at least one adjustment actuator is supported on the outer ring.
In another embodiment of the invention, the support bearing for supporting the at least one adjustment actuator can—in addition to said energy supply duct—also comprise a signal duct, especially in the form of a signal line, which connects a system disposed on the adjustment actuators that measures travel and the adjustment angle with the supply unit or with a control component on the other side of the carrier part. The support bearing can thus have a triple function: a rotatable link for the adjustment actuator, an energy supply duct, and signal transmission.
In particular, said travel measuring system for recording the adjustment movements of the at least one adjustment actuator and/or rotational movements generated by it may comprise an angle sensor and/or a linear travel sensor integrated in the adjustment actuator, wherein a signal line from the angle sensor and/or travel sensor to the control device disposed on the supply unit is being conducted through the support bearing, for example by means of sliding contacts or a suitable signal line.
Below, the invention is described in detail by means of preferred embodiments and with reference to the attached drawings.